Plastic composition



UNITED STATES PATENT OFFICE.

FRANQOIS RICHARD ANDFRAI Q'CIS M. BRADY, 0F CLEVELAND, OHIO.

PLASTIC COMPOSITION.

N 0 Drawing.

To all whom it may concern:

Be it known that we, FRANQOIS RICHARD and FRANCIS M. BRADY, citizens ofthe French Republic and United States, respectively, both residing at7800 Finney ave., city of Cleveland, in the county of Cuyahoga and Stateof Ohio, have invented a new and useful Improvement in PlasticComposition, of which the following is a specification, the principle ofthe inventionbeing herein explained and the best mode in which We havecontemplated applying that principle, so as to distinguish it from otherinventions.

Our invention pertains to a plastic composition and more particularly toa vitric composition adapted to serve as a high tension and high voltageinsulator, and besides fill a need in the manufacture of spark plugs.

The object has. been to produce a compound of the character stated whichwill be of great strength, which will be unimpaired by subjection toeven sudden changes of temperature, and which may be easilydlndeconomically manufactured in the forms desired.

The composition comprises the following ingredients (chemicalsubstances) in substantially the proportions now given.

Silica fifty-five to sixty-five (5565) per cent. Alumina twenty (20)Ferrous oxid five to nine (59) Lime one to two 51-2) Magnesia .two tothree 2-3) A1kalis s .tl1ree to five (3-5) The composition differs inappearance before and after vitrifaction'. It is whitish gray when firstmolded to shape While in a plastic state, but after becoming a fusedcompound takes on a reddish brown color. 1

The percentages are approximately as follows: Silica .sixtyper cent.Alumina a "twenty (20) per cent. Ferrous oxid .seven (7) per cent. Limev0 (2) per cent. Magnesia two (2) per cent. Alkalis our (4) per cent.

'dred degrees (800-900) Fahrenheit Specification of Letters Patent.Patented J 311. 2'7, 1920. Application filed May,2, 1917.

Serial No. 165,833.

They are too friable and are over sensitive to quick temperature changessuch as those which attend rain storms on excessively hot summer daysl.

Our invention is not merely dependent upon the essential substances norupon the relative quantities used, but is vitally dependent upon thediscovery of how best to approach the maximum degrees of heat.

The silica is the primary insulator, while the alumina and ferrous oxidlend the requisite toughness and strength respectively. The two oxids donot impair the predomi nant function of the silica as an insulatorbecause they are themselves non-conductors.

The ingredients in the percentages previously listed are found incertain natural clays and are first pulverized, then put into plasticform by the addition of a suitable amount of water and worked or moldedinto the shape desired. Next the humidity is partly driven off with adry warm air at a temperature of about one hundred degrees (100). If thehumidity is not first driven off the mass will swell, warp and crack.The temperature must be left low untilall the steam has been driven ofi.Then a gradually increasing heat is applied to-start the burning of thecarbon which is present in natural condition in such natural clay as hasproven suitable. When eight to nine hunreached thecarbon will have beenburned, and the metal oxids have fused or sintered. The carbon must beburned very slowly at temperature increases of, say, one hundred degrees(100) Fahreneit at intervals of about an hour. If the temperature isquickly raised the carbon gases inflate and disrupt the mass with theresult that a light porous clinker ensues. After the carbon is Whollyburned the temperature may be raised with any rapidity.

At sixteen hundred degrees (1600) Fahrenheit a contraction ensuestending to effect a binding action. Thereafter the temperature is raisedinto the thousands sufficiently to fuse the ferrous oxid while stillleaving the silica mainly in its natural state, that is, unfused.

The resultant vitrified product assumes a reddish brown color. The whitespecks in the sample are due to the dispensable pres-- ence of magnesia.The lime slags the silica and tends to help bind the Whole. The alkalismerely assist in some measure to efiect become partially hundred degrees(140W) which is also favorable to bind the mass.

Our composition has withstood a pressure of several tons to the squareinch. It has been heated to from eight hundred to a thousand degrees(800-1000) Fahrenheit and then suddenly nnmersed in water withoutinjurious results of any kind. It has satisfied the most extremerequirements of high tension insulation.

For practical use it would be preferable to glaze the exterior surfaceto minimize the adherence of soot in such quantity as might, ifmoistened, act as a conductor.

Another advantage which our composition has over fused aluminouscompounds such as porcelain, is that it vitrifies at lower temperatures.The temperatures required in the making of porcelain are so high as tomelt the steel cores on which it is frequently desirable and quitepossible to vitrify our composition preparatory to shrinking the formthereon. In the case of our composition it is feasible to obtain a hightension insulator having a steel core as asupport therefor by subjectingsuch support to the vitrifying temperature together with our envelopingcomposition without injury to the steel. Moreover, an economy isrealized in manufacturing our composition owing to the comparatively lowtemperatures at which the kiln may be operated.

Theemployment, together with the silica, offtwo. metal oxids which arefusible at different temperatures is an adoption which is thought toconstitute a distinguishing feature.

We claim:

1. The process of making aninsulator which consists in mixing silica andcarbon with lesser quantities of alumina and ferrous oxid with theaddition of water and a binding substance, forming the mass, driving offthe humidity by subjecting to a temperature around 100 Fahrenheit,gradually raising the temperature to 800 or 900 degrees Fahrenheit so asto burn out the carbon, thereafter rapidly increasing the heat applieduntil a contraction ensues, and finally raising the temperaturesufliciently to inciplently fuse the ferrous oxid WllllG leaving thesilica mainly unfused.

2. The above described process of producing an insulator by mixing withwater a pulverized natural clay containing about sixty per cent. ofsilica, twenty per cent. of alumina, seven per cent. of ferrous oxid andthe remaining per cent. lime, magnesia, carbon and alkalis, forming themass to desired shape, subjecting the mass to low heat over a longperiod of time until the carbon is slowly burned out, and then greatlyincreasing the heat to partiall fuse the whole.

3. The process of ma ring a vitreous insulator, which consists in mixinga pulverized clay containing carbon, silica, alumina and ferrous oxidwith enough water to make a plastic mass, shaping the same, heatingslightly for a considerable period of time to slowly drive off steam,presently increasing the temperature and malntaining it at about SOO-900until the carbon is burned out and finallygreatly increasing the heatuntil the mass is partiallyfused whereby to obtain a hard and toughproduct.

Signed by us, this 26th day of April, 1917.

FRANQOIS RICHARD. F. M. BRADY.

' Attested by- CURT B. MUELLER, PAUL MUnLLEn.

